Prior art includes the Quadrant Conical-Lens Microscope, U.S. Pat. No. 4,469,411, 9/4/84; by this inventor. This microscope has two stacks of quadrant conical lenses mounted in two adjoined microscope tubes. The lenses can be revolved into and out of the line of sight to increase and decrease the power of magnification.
The lenses are disclosed in a copending application entitled Conical Beam Concentrator. The code designation of the concentrator is M:RT-2L:C (R--refracting section (face) of a component lens, T--transmitting section of a component lens, L--reflecting section of a component lens, M--magnifying stage lens, and C--concentrating stage lens).